SOLUTION: Jim built a rectangular shed with a total floor surface area will be 126 sq.ft if the lenght is 4 feet more than twice it's width what is the width of the dog house. Please help me

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Question 941480: Jim built a rectangular shed with a total floor surface area will be 126 sq.ft if the lenght is 4 feet more than twice it's width what is the width of the dog house. Please help me with this
Found 2 solutions by srinivas.g, MathTherapy:
Answer by srinivas.g(540) About Me  (Show Source):
You can put this solution on YOUR website!
surface area of rectangular floor = 126 sq fr
let x be the width
length = 2x+4
area = length * width
126 =(2x+4)*x
+126+=+2x%5E2%2B4x
move 126 to the right
+0+=2x%5E2%2B4x-126
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 2x%5E2%2B4x%2B-126+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%284%29%5E2-4%2A2%2A-126=1024.

Discriminant d=1024 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-4%2B-sqrt%28+1024+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%284%29%2Bsqrt%28+1024+%29%29%2F2%5C2+=+7
x%5B2%5D+=+%28-%284%29-sqrt%28+1024+%29%29%2F2%5C2+=+-9

Quadratic expression 2x%5E2%2B4x%2B-126 can be factored:
2x%5E2%2B4x%2B-126+=+2%28x-7%29%2A%28x--9%29
Again, the answer is: 7, -9. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+2%2Ax%5E2%2B4%2Ax%2B-126+%29


x= 7 or -9
but x represents width. it cannot be negative
hence x= 7
width (x) = 7 feet

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
Jim built a rectangular shed with a total floor surface area will be 126 sq.ft if the lenght is 4 feet more than twice it's width what is the width of the dog house. Please help me with this 


Let width be W

Then length = 2W + 4

Since area is 126 sq feet, we get: W(2W + 4) = 126

2W%5E2+%2B+4W+-+126+=+0

2%28W%5E2+%2B+2W+-+63%29+=+2%280%29

W%5E2+%2B+2W+-+63+=+0

(W - 7)(W + 9) = 0

W, or width = highlight_green%287%29 ft             OR            W = - 9 (ignore)